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Long range organization of satellite DNAs in the genome of Tribolium madens (Coleoptera, Insecta)

Satellite DNAs are tandemly arranged highly repetitive DNA sequences that are found in genomes of all eukaryotes. Long range organization of these sequences is poorly understood. The work presented here represents the first insight into the large scale organization of satellite DNAs in insect family Tenebrionidae. Species Tribolium madens was chosen for this study because of the presence of two related satellites, and because of the existence of supernumerary chromosomes. In order to study organization of satellites I and II on long genomic segments, the method of pulsed field gel electrophoresis was performed together with fluorescence in situ hybridization on metaphase chromosomes, extended chromosomes and on extended DNA fibers. Results reveal the presence of both satellites in pericentromeric heterochromatin of all chromosomes including supernumeraries. It has been shown that two satellites are closely adjacent and that they form long uninterrupted clusters that range in size from 100 kb up to several Mb. It has been found that satellite II exhibits long range organization unusual for satellite DNA.

extended chromosomes; extended DNA fibers; long range organization; pulsed field gel electrophoresis; satellite DNA; two-color florescence in situ hybridization

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